Audi A4, S4

since 2000 release

Repair and operation of the car

Audi A4, S4
+ Introduction
+ Governing bodies and methods of safe operation
+ Current leaving and service
+ Engine
+ Cooling systems, heating and air conditioner
+ Power supply systems, release and decrease in toxicity of the fulfilled gases
- Systems of electric equipment of the engine
   + System of ignition and engine management
   - System of preheat of the diesel engine
      General information
      Removal and installation of candles of an incandescence
      Check of candles of an incandescence
   + Diagnostics of systems of electronic control and diagnostic equipment
   + Systems of charging and start
+ Manual box of gear shifting
+ Automatic transmission
+ Coupling, power shafts and differential
+ Brake system
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment


System of preheat of the diesel engine

General information

On the cold diesel engine, at compression of air in cylinders, temperature, necessary for fuel spontaneous ignition, is not reached. For this reason preheat is required.

For this purpose in each combustion chamber the glow plug is established. The glow plug consists of the case with a heating core, vpressovanny in it. The heating core in turn consists of a heating spiral and an adjusting spiral. After giving of tension the heating spiral in a core heats up within several seconds to temperature + 850 °C. Thus the current passing on a candle reaches 30A. At increase in heating the spiral resistance that limits current to 15 - 25 increases And. When the control lamp of preheat on the dashboard dies away, the engine can be started.

The preheat time necessary for start of the engine makes no more than 10 pages. Time is regulated by the relay of preheat and the control unit of the engine which via the sensor of temperature of cooling liquid receives information on the current temperature of the engine. The control unit of the engine on the basis of the received information makes the decision on duration of inclusion of candles of an incandescence and necessary current of heating.

On the diesel engine with direct injection preheat is required only at a temperature below 0 °C.